Pipe welding apparatus and methods therefor

ABSTRACT

The pipe welding apparatus includes a longitudinally movable welding station, a longitudinally movable nest housing a traveller including a pipe aligner and expander and a traction assembly. A pair of pipe sections are butted one to the other and the welding station is displaced into alignment with the joint. The nest is moved to an end of a pipe section remote from the joint and the traveller moves from the nest through the pipe section to the joint. The pipe aligner and expander has a plurality of circumferentially arranged shoes which move radially outwardly to enlarge the butting end portions of the pipe sections and to draw the pipe sections axially toward one another when welding. The welding station includes an induction welder. Upon completion of the welding, the traveller returns to the nest.

[451 Oct. 10, 1972 [541 PIPE WELDING APPARATUS AND METHODS THEREFOR [72]Inventor: John Christopher, Redwood City,

Calif.

[73] Assignee: Santa Fe International Corporation, Los Angeles, Calif.

[22] Filed: Jan. 21, 1971 [21] Appl. No.: 108,383

[52] US. Cl. ..2l9/8.5, 219/60, 219/161 Pickard ..219/60 R Jackson eta1. ..2l9/l6l Primary Examiner-J. V. Truhe Assistant Examiner-Hugh D.Jaeger Attorney-Le Blanc & Shur [5 7] ABSTRACT The pipe weldingapparatus includes a longitudinally movable welding station, alongitudinally movable nest housing a traveller including a pipe alignerand expander and a traction assembly. A pair of pipe sections are buttedone to the other and the welding station is displaced into alignmentwith the joint. The nest is moved to an end of a pipe section remotefrom the joint and the traveller moves from the nest through the pipesection to the joint. The pipe aligner and expander has a plurality ofcircumferentially arranged shoes which move radially outwardly toenlarge the butting end portions of the pipe sections and to draw thepipe sections axially toward one another when welding. The weldingstation includes an induction welder. Upon completion of the welding,the traveller returns to the nest.

30 Claims, 16 Drawing Figures PATENTED 10 1973 3.697. 720

SHEET 1 OF 6 ATTORNEYS INVENTOR JOHN CHRISTOPHER PATENTED'ncI 10 1912saw 2 0F 6 PATENTEDum 10 I972 SHEET 3 0F 6 PATENTEnum 10 I972 SHEET 5 BF6 kw mk PATENTEDUCT 10 m2.

SHEEI 6 [1F 6 PIPE WELDING APPARATUS AND METHODS THEREFOR The presentinvention relates to pipe weldingapparatus and methods therefor andparticularly relates to apparatus and methods for aligning anddiametrically enlarging the ends of pipe sections adjacent the joint andbutt welding the pipe ends-one to the other utilizing induction weldingtechniques.

Induction welding of the ends of pipe sections one to the other has beenaccomplished in the past. In many such prior art welding apparatus, theends of the pipe sections are clamped one to the other and inductivelycoupled whereby a forge type weld between the pipe sections is effected.In providing the welded joint, prior welding apparatus usually employpipe aligners which axially align the pipe section ends eitherexternally or internally of the pipe sections depending on the typeemployed. One such internal pipe aligning apparatus is described andillustrated in U.S. Pat. No. 2,615,413. In

that patent, there is disclosed two groups of a plurality of shoes eachrespectively circumferentially arranged about a cylinder and a piston.Movement of the cylinder with the piston fixed extemallymoves the shoesassociated therewith radially into engagement with the inner wall of oneof the pipe sections. Thereafter and after release of the piston, thelatter moves relative to the cylinder to move its shoes radially intoengagement with the walls of the other pipe section. Thereafter,relative movement of the piston and cylinder circularizes the ends ofthe pipe sections as well as draws the pipe sections together. It hasbeen found, however, that a cold working of the metal about the pipeends prior to welding provides a superior welded joint. The device ofU.S. Pat. No. 2,615,413 is apparently incapable of uniformlydiametrically expanding the ends of the pipe sections to provide a coldworking of the metal. Moreover, the shoes of such prior pipe aligningapparatus may become misaligned whereby the shoes are cocked one to theother. When the shoes are cocked, the pipe ends cannot, of course, becircularized. Furthermore, it has in the past been difficult to locatethe pipe aligner at the precise location of the joint. That is to say,it has been difficult to locate the aligner as it moves within the-pipesection in a manner such that the pipe ends are gripped on oppositesides of the joint a uniform distance from the joint. Still further,sequential engagement of the aligner with the pipe sections, as in U.S.Pat. No. 2,615,413,

may cause the aligner to move into misalignment with the joint even whenthe pipe aligner is initially properly located relative to the joint.

The present invention provides an improved pipe welding apparatus andmethods therefor which overcomes the previously noted and otherobjections and difficulties surrounding prior pipe welding apparatus andmethods and provides a novel and improved pipe welding apparatus andmethods therefor which eliminates or minimizes the disadvantagesassociated with the prior pipe welding apparatus and provides variousadvantages thereover. To this end, the present invention provides alongitudinally movable welding station including an induction coil forsurrounding the joint, the coil being diametrically split with the coilhalves movable toward and away from one another. The apparatus alsoincludes a nest housing a traveller including a traction assembly formoving the traveller within the pipe sections and a pipe aligner andexpander for obtaining coaxial relation of the pipe sections anddiametrically enlarging and cold working the metal of the pipe sectionends adjacent the joint. Utilizing the pipe welding apparatus andmethods hereof, the pipe sections are located in end to end buttingrelation and the welding station is displaced to locate the inductioncoil in position surrounding the joint. The nest is moved into alignmentwith the end of one of the pipe sections remote from the joint and, byactuating the traction assembly, the traveller moves from the nestthrough the one pipe section toward the joint.

It is a particular feature of the present invention that the pipealigner and expander hereof can be precisely located with the pipesections relative to the joint. To accomplish this, there is provided areel on the movable welding station, the line from which extends about apair of spaced fixed pulleys and is secured at one end to the travellerassembly. Thus, once the length of the pipe section to be welded isknown, the length of line payed out from the reel is deterrninitive ofthe location of the traveller within the pipe sections. By constructingthe traction assembly to be responsive to a predetermined length of linepayed out from the reel to stop the traveller within the pipe section,the traveller can be precisely located within the pipe sections relativeto the joint.

Once the pipe aligner and expander is precisely located within the pipesections,-a fluid actuated piston and cylinder arrangement operates tosubstantially simultaneously engage a plurality of circumferentiallyspaced shoes againstthe inner walls of the pipe section ends on eitherside of the joint to axially align the pipe sections, enlarge thediameter of the pipe sections at the joint to a uniform diameter, coldwork the metal of the pipe section ends at the joint by such diametricalenlargement and axially displace the pipe sections toward one another.The pipe aligner and expander per se contains many novel featuresincluding apparatus for maintaining the shoes in axial alignment onewith the other and maintaining a simultaneous uniform radial movement ofthe shoes. Also, there is provided an apparatus for preventing cockingof the shoes whereby circularization of the pipe section ends isensured. It is also a further feature hereof that apparatus is providedfor maintaining the pipe aligner and expander in its precisely locatedposition relative to the joint when the piston and cylinder of the pipealigner and expander move relative to one another to engage the shoesagainst the inner walls of the pipe sections. To accomplish this, thepipe aligner and expander is mounted for movement relative to thetraction assembly whereby relative movement of the piston and cylinderin equal increments in opposite axial directions is assured. That is tosay, the location of the traction assembly relative to the joint ismaintained at a constant fixed distance when the pipe aligner andexpander is actuated and which actuation might otherwise tend todislocate the pipe aligner and expander relative to the joint.

Accordingly, it is a primary object of the present invention to providenovel and improved pipe welding apparatus and methods therefor.

It is another object of the present invention to provide a novel andimproved pipe welding apparatus ineluding a traveller assembly carryinga pipe aligner and expander wherein the traveller assembly can bedisplaced along the pipe sections and precisely located within the pipesections relative to the joint.

It is still another object of the present invention to provide animproved pipe welding apparatus including a pipe aligner and expanderwhich serves to diametrically expand and hence cold work the metal ofthe pipe section ends prior to welding.

It is a further object of the present invention to provide a pipewelding apparatus including a traveller assembly comprised of a pipealigner and expander and a traction assembly wherein the relativeposition of the traction assembly and the joint is maintainedirrespective of the movements of the various parts of the pipe alignerand expander in engaging, expanding and drawing towards one another endends of the pipe sections on opposite sides of the joint.

It is a still further object of the present invention to provide novelpipe welding apparatus including a longitudinally movable nest forhousing the traveller, and a longitudinally movable welding station.

These and further objects and advantage of the present invention will bemore apparent upon reference to the following specification, appendedclaims and drawings wherein:

FIG. 1 is a fragmentary vertical cross sectional view of a pair ofbutting pipe sections illustrated in position for welding utilizing apipe welding apparatus constructed in accordance with the presentinvention;

FIG. 2(a) and FIG. 2(b) are vertical cross sectional views of the pipewelding apparatus hereof particularly illustrating a pipe aligner andexpander in FIG. 2(a) and a traction assembly therefor in FIG. 2(b),FIG. 2(b) forming a continuation of FIG. 2(a) along the dashed line atthe right hand end of FIG. 2(a);

FIG. 3 is a transverse sectional view through a pipe section generallytaken about on line 3-3 in FIG. 1 and illustrating the pipe weldingstation and the pipe aligner and expander within the pipe section at thewelding station;

FIG. 4 is a cross sectional view of the pipe aligner and expandergenerally taken about on line 44 in FIG. 1;

FIG. 5 is a transverse cross sectional view of the pipe aligner andexpander taken about on line 5-5 in FIG.

FIGS. 6 and 7 are transverse cross sectional views of the tractionassembly and taken generally about on lines 6-6 and 77 respectively inFIG. 1;

FIG. 8 is an enlarged fragmentary cross sectional view illustrating aportion of the induction welder and a pipe joint at the pipe weldingstation;

FIG. 9 is a perspective view of a pin connecting between longitudinallyadjacent shoes of the pipe aligner and expander illustrated in FIG.2(a);

FIG. 10 is a perspective view of a shoe utilized in the pipe aligner andexpander illustrated in FIG. 2(a);

FIG. 11 is a schematic diagram of a fluid circuit for the pipe weldingapparatus hereof; and

FIGS. 12-15 are schematic elevational views with parts in cross sectionillustrating the manner in which the pipe sections are butt welded oneto the other.

Referring now to the drawings, particularly to FIGS. 1 and 12, there isillustrated a pair of pipe sections 10 and 12 in spaced, generallycoaxial, alignement, which pipe sections are to be butt welded one tothe other utilizing the pipe welding apparatus hereof. The pipe weldingapparatus comprises a traveller T for movement within the pipe sectionsand including a pipe aligner and expander generally indicated 14 atraction assembly generally indicated 16. The traction assembly 16 isutilized to advance pipe aligner and expander 14 through one of the pipesections to locate it in a predetermined position relative to the pipejoint J formed at the abutting ends of pipe sections 10 and 12, tomaintain the pipe aligner and expander 14 in such predetermined positionduring welding, and to withdraw or retract the pipe alinger and expander14 through the pipe after the weld is accomplished. There is alsoillustrated in FIG. 1 a pipe welding station generally indicated 18which, in the embodiment herein disclosed, comprises an induction buttwelder more particularly described hereinafter.

Referring now in detail to the pipe aligner and expander 14 andparticularly to FIGS. 2(4) 4, 5 and 10, there is illustrated a cylinder20 defining a chamber 22 with an end plate 24 fixed to cylinder 20. Thebase portion 26 of cylinder 20 comprises a truncated conically shapedelement having a central passage 28, Longitudinally adjacent and inaxial alignment with cylinder 20 is a similar truncated conically shapedelement 30 having an end plate 32 suitably secured thereto by bolts 34(FIG. 3). Conical element 30 has'a central passage 34 in axial alignmentwith passage 28. A piston 36 is provided and includes a piston head 37received in chamber 22 and a piston shaft 38 slideably receivable inpassages 28 and 34 of conical elements 26 and 30, respectively. Thepiston shaft 38 is secured at an end remote from head 37 to end plate32. A suitable O-ring seal 40 is provided about piston head 37 inchamber 22. Piston 36 is tapped as at 42 and threadedly receives the endnipple of a rod 44, the latter being slideably received through acentral opening 46 in end plate 24. Rod 44 has an axial passage 48which, in conjunction with a passage 50 formed in piston 36, lies incommunication with chamber 22(a) on the inner side of piston head 37. Atapped opening 52 is provided in end plate 24 and a suitable fitting 54(FIG. 2(b)) is provided for communicating pressure fluid to and fromchamber 22(b) on the opposite side of piston head 37. It will thus bereadily appreciated that cylinder 20 including element 26 and plate 24is relatively axially movable with respect to piston 36 includingelement 30 and end plate 32.

As particularly illustrated in FIGS. 2(a) and 4, a like number of aplurality of shoes 56 are circumferentially spaced about the conicalsurfaces of each of elements 26 and 30. For example, in FIG. 4, there isillustrated twelve shoes disposed about element 26 of cylinder 20 and,accordingly, a like number of shoes 56 are also circumferentially spacedabout element 30. The shoes 56 are mounted for axial and radial slidingmovement in a manner as will now be described.

The lateral surfaces of conically shaped elements 26 and 30 areidentical and a description of one, for example, with respect to theelement 26 illustrated in FIG. 4, is believed sufficient as adescription of the other. Referring to FIG. 4, conical element 26 has aplurality of flat sides 58 disposed circumferentially thereabout andequal in number to the number of shoes 56 thereabout. A tongue andgroove type connection is provided between each of the shoes and itsassociated underlying flat face 58. Particularly, each face 58 isprovided with a groove 60 which extends along and parallel to thesurface 58in an axial direction. A tongue 62 is provided along theunderface of each of shoes 56, the tongue 62 extending in an axialdirection and having a slope corresponding to the slope of groove 62whereby the corresponding shoe 56 is axially slideable relative toelement 26. It will be appreciated that relative axial movement betweenshoes 56 and the conical shaped elements 26 and 30 provides for radialexpansion and retraction of shoes 56 when the shoes lie in a fixed axialposition. As will be appreciated in FIG. 10, the outer faces 64 of shoes56 are arcuate to conform to the inner surface of the pipe sections inwhich the particular pipe aligner and expander is to be utilized. Byproviding a plurality of shoes 56 circumferentially spaced about thepipe aligner and expander and providing a generally arcuate outersurface 64 on the shoes, it will be appreciated that the outer surfacesof the shoes form a substantially uninterrupted sleeve in a diametralplane of the pipe.

The shoes 56 on the respective elements 26 and 30 are mounted foruniform radial expansion and contraction and also provide, in use, aconstant gripping force on the ends of the pipe sections substantiallyuniformly about their inner peripheries. To accomplish these ends, theshoes on the respective elements 26 and 30 are maintained in axialalignment one with the other and are also connected one to the other forrelative uniform axial sliding movement. Each shoe is provided adjacentits larger end with a radially extending tapped bore 70 and an axiallyextending recess 72 opening through the large end face of the shoe andin communication with bore 70. As best illustrated in FIGS. 2(a) and 9,opposite ends of pins 74 are received within the axially alignedopenings 72 of each pair of axially aligned shoes 56. Each pin 74 has anelongated cutout 76 along one side thereof with its opposite ends 78forming radially projecting lugs 78. Bolts 80- are received in passages70 of the axially aligned shoes 56 and extend within the cutout 76 ofpin 74. A pair of alignment discs 82 are provided about piston shaft 38on the opposed ends of the conical elements. Each alignment disc 82(FIGS. 2(a) and 5) includes a plurality of circular recesses 84 spacedcircumferentially about shaft 38. When discs 82 are in axial andcircumferential alignment one with the other, the recesses 84 of therespective discs lie in axial alignment each with the other and receivecompression springs 86 for biasing the discs axially away from oneanother. A plurality of radially extending cutouts are circumferentiallyspaced about the periphery of each of the alignments discs 82, thecutouts 88 opening outwardly through the outer edges of discs 82. Whenassembled, pins 74 are disposed within cutouts 88 and the portions 89 ofthe discs 82 between the cutouts 88 bear against respective end faces ofshoes 56. Thus, the axially aligned shoes 56 are biased away from oneanother and also maintained in predetermined axial and circumferentialrela tion one with the other. By the foregoing described arrangement,coil springs 86 maintain a uniform maximum gap between the shoes whenrelaxed up to the time shoes 56 grip the interior walls of the pipesections as described hereinafter. A pair of spacer rings 90 areprovided between the reduced ends of shoes 56 and shoulders formed oncylinder 20 and end plate 32 to limit the radial expansion of shoes 56.That is to say, spacer rings 90 determine the maximum final interiordiameter of the pipe at the joint. The alignment discs 82 also preventcocking of the shoes 56 at different diametrical positions. Also mountedon end plate 32 is a wheel 92 which, in conjunction with tractionassembly 16, provides for traversing movement of the traveller T withinthe pipe sections.

Turning now to FIG. 2(b), there is illustrated, in detail, tractionassembly 16 which comprises a frame including a pair of frame plates 102transversely spaced one from the other by a pair of longitudinallyspaced stiffeners 104 and a transversely extending shaft 106. A pair ofidler arms 108 are pivotably mounted on shaft 106 and at one end mountan idler wheel 110 for engagement along the upper interior wall of thepipe section in which the pipe aligner and expander 14 is disposed.Along the lower side of frame 100 and between frame plates 102, there isprovided a rod 112 extending longitudinally between stiffeners 104. Ablock 114 is slideably carried by rod 112. Block 114 lies between thelower ends of idler arms 108 and has a pair of laterally extending stubshafts 116 received in substantially vertically extending slots 118opening through the lower ends of idler arms 108. A compression spring120 is carried by rod 112 and biases block 114 for sliding movement fromleft to right as seen in FIG. 2(b) whereby idler arms 108 are biased forcounterclockwise rotation with the result that idler wheel 110 iscontinuously biased against the upper interior wall of the pipe section.As best illustrated in FIG. 6, a

. forward portion of frame 100 is carried by a pair of wheels 122suitably mounted on an axle 124 carried by frame plates 102. It will benoted that the edges 123 of wheels 122 are beveled for conformity withthe arcuate surface of the pipe section. Also, idler wheel 1 10 has aconvex surface for conformity with the arcuate interior wall of the pipesection.

A motor mounting plate 126 is preferably welded along the underside offrame plates 102 and a drive housing 128 forming a part of driveassembly, generally indicated 130 is suitably secured thereto. Driveassembly 130 includes a reversible fluid actuated motor 132 which drivesa worm gear 134 (FIG. 7). Worm gear 134 extends axially within a drivehousing 128. Housing 128 in conjunction with a housing cover 136 carriesa worm gear 137 splined to an axle 138, worm gear 137 lying in meshingengagement with worm 134. Axle 138 carries a pair of drive wheels 139,the edges of which are beveled to conform to the inner arcuate wall ofthe pipe section. It will thus be appreciated that actuation of motor132 in forward or reverse directions drives wheels 140 through the wormand worm gear transmission for driving traveller T in forward andreverse directions through the pipe section.

When the pipe aligner and expander 14 is properly located within thepipe sections adjacent the joint J, it is important to maintain thisposition for welding particularly when shoes 56 are expanded to engagethe inner pipe wall. To prevent axial dislocation of the pipe alignerand expander 14 and traveller assembly 16 in the pipe when the fluidmotor comprising piston 36 and cylinder of the expander is actuated in amanner to be described, the distance between traveller frame assembly100 and the gap between the axially spaced shoes remains constantthroughout their radial expansion and axial movement toward one another.To this end, there is provided a pinion 140 carried on a pinion shaft142 joumalled between frame plates 102. A rack 144 is suitably securedto cylinder end plate 24 and lies in meshing engagement with pinion 140on one side thereof. A tail rod rack 146 is secured to the tail end ofrod 44 and lies in meshing engagement with pinion 140 on its other side.A pair of brackets 148 are secured to end plate 24 and projectrearwardly on opposite sides of traveller frame 100. Brackets 148 carryrollers 150 which engage in tracks 151 on the outer sides of plates 102,the tracks 151 being formed by vertically spaced bars 152. In thismanner, relative movement between traction assembly 16 and pipe alignerand expander 14 is provided. That is to say, when cylinder 20 and itsend plate 24 are axially displaced to the left as seen in FIG. 2(a) toradially expand shoes 56, piston 36 is axially displaced to the right anequal distance through the connection between cylinder 20 and piston 36comprising racks 144 and 146 and pinion 140. Thus, cylinder 20 may bedisplaced axially toward and away from frame assembly 100 with rollers150 travelling in tracks 151 of frame assembly 100. In this manner, whenthe shoes 56 are located in position on opposite sides of the joint,axial movement of the cylinder 20 and piston 36 is in equal incrementsin opposite directions whereby shoes 56 are maintained in the selectedaxial position relative to the joint.

To power the carriage through the pipe sections as well as to expand andretract shoes 56 into and out of engagement with the inner walls of thepipe sections, there is provided a hydraulic circuit best illustrated inFIG. 11. In FIG. 11, there is provided a pressure compensated variablevolume pump 160 in communication on one side with a hydraulic fluidreservoir and on its other side with a four-way three position springcentered solenoid actuated valve 162. Solenoids 164 and 166 are providedon either side of valve 162 and, when actuated, shift the valve indirections opposite from the side on which the solenoids areillustrated. A fluid line 168 connects between valve 162 and a two-waytwo position valve 170 which is actuated for movement to the left asseen in FIG. 11 by a solenoid 172 and which has a spring return 174. Afluid outlet line 176 communicates between valve 170 and one side ofpiston 36 in cylinder 20, and an exhaust line 178 communicates betweenthe opposite side of piston 36 in cylinder 20 and a fluid line 180. Oneend of line 180 communicates with valve 162 and its other endcommunicates with a fluid line 182. Fluid line 182 communicates withreversible hydraulic motor 132 and also with a pressure actuated switch184. Switch 184 is electrically connected to solenoid 172 as indicatedby the dashed line in FIG. 11. The outlet side of motor 132 communicatesvia hydraulic line 186 with valve 170.

The operation of the hydraulic circuit will now be described. To movepipe traveller T through a pipe section to a location adjacent joint J,solenoid 164 is actuated to shift valve 162 to provide pressure fluidfrom pump 160 through fluid lines 168 and 186 to drive motor 132 in aforward direction'with the pressure fluid returning via fluid lines 182and 180 through valve 162 to reservoir 188. As will be describedhereinafter, a limit switch, actuatable in response to locating pipealigner and expander 14 within the pipe sections adjacent the pipejoint, de-energizes solenoid 164 whereby valve 162 is returned to itsspring centered position preventing further operation of motor 132. In

the case of overshoot solenoid 166 is energized by the same limitswitch, reversing motor 132, and thus returning traveller to correctalignment when both solenoid 166 and 164 are de-energized. To relativelydisplace the piston and cylinder and thereby expand the shoes radially,solenoid 164 is again actuated to shift valve 170 to the left as seen inFIG. 11 to provide pressure fluid from pump through fluid lines 168 and176 into chamber 22(b). After welding is completed, solenoid 164 isde-energized and solenoid 166 is energized to shift valve 162 to theleft as seen in FIG. 11 to provide pressure fluid from pump 160 throughfluid lines 180 to motor 132 and pressure switch 184. With valve shiftedto the left as seen in FIG. 11, the return line 186 from motor 132 isblocked by valve 170 which remains shifted to the left whereby motor 132cannot be operated. By shifting valve 162 to the left, pressure fluid issupplied chamber 22(a) via fluid lines and 178 and fluid in chamber22(b) is returned to reservoir 188 via lines 176 and 168. After suitabletime delay, pressure build-up in fluid lines 180 and 182 actuatespressure actuated switch 184, which, in turn, de-energizes solenoid 172whereby valve 170 is spring biased to the right to provide communicationbetween fluid line 186 and reservoir 188 via fluid line 168. Pressurefluid supplied to motor 132 via lines 180 and 182 thus operates motor132 in the reverse direction whereby the traveller T is withdrawn fromthe pipe section.

Referring now to FIG. 3, there is illustrated, in detail, the weldingstation 18 comprising a support structure including a pair oflongitudinally extending beams 180 supporting tracks 182. A pair ofbushings 184 are mounted on opposite sides and on the underside of a boxframed carriage 186, bushings 184 engaging tracks 182 for slidingmovement of carriage 186 therealong. The carriage 186 carries adepending fluid motor 188 mounting a pinion 190 which engages a rack 192disposed along the underside of the upper flange of a beam 180 wherebycarriage 186 may be longitudinally displaced along tracks 182 toselected positions by operation of motor 188. A brake 194 is provided onthe underside of carriage 186. Carriage 186 includes a pair ofupstanding supports 196 which, in turn, carry semicircular inductorshields 198 and inductors 200 enclosed with inductor shield 198.Suitable clamping devices 202 clamp the semi-circular inductor shields198 one to the other and provide electrical connections at diametricallyopposite positions for the semi-circular inductor coils within theinductor shield. Thus, inductor coils 200 are arranged substantiallycircularly about a pipe section received between the supports 196.Cooling water circuits, not shown, are provided each semi-circular coil200 for flow of cooling water therethrough. A suitable housing 204 onone side of welding station 18 contains a transformer and suitablecontrols for operating the induction welding apparatus.

The supports 196 are slideably mounted on inductor carriage 186 fortransverse movement toward and away from one another whereby inductorcoil 200 can be disposed about the joint. Also, the transverse slidingmovement permits movement of the welded pipe through the welding stationwithout interference from the welding apparatus. The inductor shield 198is best illustrated in FIG. 8 and comprises a Fiberglass ring forspacing inductor coil 200 equidistant from the pipe joing for allcircumferential positions thereabout. To weld the joint and in apreferred form hereof, a 3,000- cycle alternating current is providedthrough the inductor coil and induces a current in the pipe at thejoint. The PR losses liberate heat which is conducted through to theinner surfaces of the pipe whereby the joint is forge welded.

Referring now to FIGS. 12-15, there is mounted a cable reel 210 oncarriage 186 carrying a cable 212. Cable 212 extends from reel 210 andis wrapped about a apir of pulleys 214 longitudinally spaced one fromthe other a distance at least as great as the sum of the maximum lengthof a pipe section to be welded, the max-. imum distance of longitudinaltravel of the welder, and a distance equal in length to nest 216. Cable212 also extends about a fixed elevated pulley 215 whereby the cableobtains an elevation locating it for disposition in the pipe sections.The end of the cable is suitably secured to the frame assembly 100. Alimit switch 218 is carried on carriage 186 and is actuated in responseto the paying out of a predetermined length of cable 212 for reasonsdescribed hereinafter.

Traveller T is carried in a nest 216 comprising an elongated tubularsection 218 mounted on platform 220. Platform 220 has pairs of wheels 22engaging along tracks 182 and it will be appreciated that nest 216 andthe traveller T therein are mounted for longitudinal movement alongtracks 182. The hydraulic lines for traveller T are carried abouttake-up reels schematically illustrated at 224 whereby such lines aremaintained in a substantially taut condition for all longitudinaldispositions of traveller T within pipe sections 10 and 12. The forwardend of nest 216 is flared outwardly as at 226 for receiving therearrnost end of pipe section 12. When it is desired to weld the forwardend of pipe section 12 to the rear end of pipe section 10, pipe section12 is located in a lineup station as indicated in FIG. 12 between theinductor welder 18 and nest 216. Nest 216 is then advanced such that therear end portion of pipe section 12 is received within the flared end226 of nest 216. Also, by operation of suitable controls for motor 188,the inductor welder 18 is longitudinally displaced along tracks 182 toalign inductor 200 with the rear end of pipe section 10, as particularlyillustrated in FIG. 13. Simultaneously, the pipe section 12 and nest 216are longitudinally displaced toward pipe section 10 by suitable means,not shown.

Also, solenoid 164 is energized to shift valve 162 to the right as seenin FIG. 11 to provide pressure fluid to motor 132 whereby traveller Tadvances from nest 216 into pipe section 12 and therealong toward jointI at the opposite end of pipe section 12. It will be appreciated that apredetermined length of cable 212 extends from cable reel 210 totraveller T when the shoes 56 are aligned on either side of pipe joint Jfor any longitudinal displacement of welder 18. That is to say,

once the location of reels 214 and 216 are fixed, limit switch 218 isactuated by the unreeling of a predetermined length of cable 212.Actuation of limit switch 218 de-energizes solenoid 164 whereupon valve162 returns to its center position stopping flow of pressure fluid tomotor 132. With the fluid supply to motor 132 thus stopped, it acts as abrake locating the aligner and expander 14 in the predetermined positionwith axially spaced shoes 56 on either side of the butt joint J. Shouldthe expander 14 overshoot the joint J, the motor 132 will reverse andthe traveller T will hunt for the proper position relative to joint J.It will be appreciated that pipe aligner and expander 14 is thus locatedwith respect to the butt joint for any longitudinal disposition ofwelder l8 and location of joint J within the range of longitudinalmovement of the welder. Once positioned, an operator, through suitablecontrols not shown, actuates the pipe aligner and expander 14 andwelding apparatus to follow a programmed sequence as follows. Solenoids164 and 172 are energized to shift valve 162 to the right and valve 170to the left respectively in FIG. 11 to supply pressure fluid to cylinder20 via fluid lines 168 and 176. As noted previously, relative movementbetween piston 36 and cylinder 20 occurs through the rack and piniontransmission resulting in equal axial displacement of the conicalelements 26 and 30 toward one another and consequent radial outwardmovement of shoes 56 to engage the inner walls of the pipe sections 10and 12 on opposite sides of joint J. Further radial movement of shoes 56causes the end portions of pipe sections 10 and 12 to enlargediametrically whereby roundness and accurate axial alignment of the pipesections is assured. The diametrical enlargement also cold works themetal pipe joint and produces an upset for forming the weld joint.Furthermore, axial movement of the conical elements toward one anotheris transmitted to the pipe sections through shoes 56. The ends of thepipe sections are thus urged toward and engage one another underpressure. Electrical current is then provided through the inductor topreheat pipe sections at their joint to a temperature approximating600F., the temperature being maintained for approximately 2 minutes.Thereafter, the inductor is supplied with full current to obtain awelding temperature of approximately 2300F. in the ends of the pipe andthis temperature is maintained for a period of slightly less than 2minutes. The pipe sections are displaced toward one another under axialpressure when the welding temperature is obtained and the sections areactually shortened in length when welded. After the welded joint isformed, the programmed sequence provides for energization of solenoid166 to shift valve 162 to the left as seen in FIG. 11 to providepressure fluid to motor 132 and pressure switch 184 while solenoid 172remains energized to vent pressure fluid in chamber 22(b) to reservoir188. Upon reaching a predetermined pressure in fluid line 182, pressureswitch 184 is actuated to deenergize solenoid 172 whereby valve shiftsto the right to provide a return fluid circuit to reservoir 188 viafluid lines 186 and 168. Motor 132 then operates in a reverse directionretracting traveller T along pipe section 12 and into nest 216. Thewelded pipe is then moved away from the welding station or the latter ismoved away from the former. The operation may then be repeated foradditional pipe sections.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. A traveller for disposition within a pair of butting pipe sectionsforming a pipe joint comprising; means for moving said travellerlongitudinally along the pipe sections including a traction assemblyengageable with the inner walls of one of the pipe sections, a pipealigner and expander coupled to said traction assembly, said pipealigner and expander including a pair of longitudinally spaced elementsmovable axially toward and away from one another, a plurality of shoesdisposed in spaced circumferential relation about each of said elementsand mounted thereon for movement radially outwardly to engage the innerwalls of the adjacent ends of the pipe sections in response to relativemovement of said elements, the respective shoes at like circumferentialpositions about said elements lying in axial alignment one with theother, a plurality of longitudinally extending pins, each of said shoeshaving a recess opening in the direction of the corresponding axiallyaligned shoe, the ends of said pins being receivable in said recesses.

2. The traveller according to claim 1 wherein the respective shoes atlike circumferential positions about said elements lie in axialalignment one with the other, and means for maintaining the shoescarried by said elements in respective axial alignment at eachcircumferential location of said shoes about said element.

3. The traveller according to claim 1 including means carried by saidpipe aligner and expander for maintaining the shoes on each said elementin a common diametrical plane thereby to preclude cocking of the shoeson said elements.

4. The traveller according to claim 1 including means for retaining theends of said pins in said recesses.

5. The traveller according to claim 1 wherein said elements lie incoaxial relation each to the other and are generally truncated conicalin shape with their smaller ends facing one another, and means mountingsaid shoes for sliding movement along the conical surfaces of saidelements in a direction having axial and radial components. 1

6. The traveller according to claim 5 wherein said shoes have arcuateouter surfaces substantially conforming to the arcuate inner walls ofthe pipe sections, a pair of discs disposed between said shoes, andmeans for biasing said discs axially away from one another and intofollowing engagement with said shoes.

7. The traveller according to claim 1 where in one of said elementsincludes a cylinder, a piston in said cylinder carrying a shaftslideably received in a central passage through said one element, saidshaft being coupled to the other of said elements, said moving meansincluding a fluid pressure source, fluid conduits for communicatingpressure fluid between said cylinder on opposite sides of said pistonand said fluid pressure source, and means for selectively communicatingfluid pressure to said cylinder on opposite sides of said piston to movesaid elements toward and away from one another.

8. The traveller according to claim 1 including means coupled betweensaid traction assembly and said pipe aligner and expander for obtainingmovement of said elements in substantially equal increments toward andaway from one another thereby to preclude movement of the traveller inthe pipe sections when said shoes are moved radially outwardly.

9. The traveller according to claim 8 wherein said coupling meansincludes a pinion rotatably carried by said traction assembly, a firstrack carried by said cylinder and in meshing engagement with saidpinion, and a second rack carried by said piston and in meshingengagement with said pinion.

10. The traveller according to claim 1 ina welding apparatus including awelding station movable longitudinally for alignment with the pipejoint, and means coupled between said welding station and said travellerfor locating said traveller in a predetermined axial position.

11. The traveller according to claim 10 wherein said welding apparatusincludes a frame, and arcuate inductor coils carried by said frame formovement between a first position substantially encompassing the pipejoint and a second position spaced from the pipe joint.

12. A traveller for disposition'within a pair of butting pipe sectionsforming a pipe joint comprising; means for moving said travellerlongitudinally along the pipe sections including a traction assemblyengageable with the inner walls of one of the pipe sections, a pipealigner and expander coupled to said traction assembly, said pipealigner and expander including a pair of longitudinally spaced elementsmovable axially toward and away from one another, a plurality of shoesdisposed in spaced circumferential relation about each of said elementsand mounted thereon for movement radially outwardly to engage the innerwalls of the adjacent ends of the pipe sections in response to relativemovement of said elements, said elements lying in coaxial relation eachto the other and being generally truncated conical in shape with theirsmaller ends facing one another, means mounting said shoes for slidingmovement along the conical surfaces of said elements in a directionhaving axial and radial components, said shoes having arcuate outersurfaces substantially conforming to the arcuate inner walls of the pipesections, a pair of discs disposed between said shoes, means for biasingsaid discs axially away from one another and into following engagementwith said shoes, the respective shoes at like circumferential positionsabout said elements lying in axial alignment one with the other, aplurality of longitudinally extending pins, each of said shoes having arecess opening in the direction of the corresponding axially alignedshoes, said discs having slots circumferentially spaced thereabout andopening through the outer edges thereof, opposite ends of said pinsbeing receivable in said recesses with intermediate portions of saidpins being receivable in said slots.

13. A traveller for disposition within a pair of butting pipe sectionsforming a pipe joint comprising; a motor operated traction assemblyengageable with the inner walls of one of the pipe sections for movingsaid traveller longitudinally along a pipe section, a pipe aligner andexpander coupledto said traction assembly for movement therewith, saidpipe aligner and expander including a pair of longitudinally spacedelements movable axially toward and away from one another, said elementslying in coaxial relation one to the other and having a generallytruncated conical shape with their smaller ends facing one another, aplurality of shoes disposed in spaced circumferential relation about andalong the conical surfaces of each of said elements and carried therebyfor sliding movement radially outwardly in response to axial movement ofsaid elements toward one another, the respective shoes at likecircumferential positions about said elements lying in axial alignmentone with the other, a plurality of longitudinally extending pins, eachof said shoes having a recess opening in the direction of thecorresponding axially aligned shoe, the ends of said pins beingreceivable in said recesses, and means carried by said traveler forsubstantially simultaneously moving said elements axially toward oneanother thereby to move said shoes radially outwardly into engagementwith the inner walls of the adjacent ends of the pipe sections.

14. A traveller for disposition within a pair of butting pipe sectionsforming a pipe joint comprising; a motor operated traction assemblyengageable with the inner walls of one of the pipe sections for movingsaid traveller longitudinally along a pipe section, a pipe aligner andexpander coupled to said traction assembly for movement therewith, saidpipe aligner and expander including a pair of longitudinally spacedelements movable axially toward and away from one another, said elementslying in coaxial relation one to the other and having a generallytruncated conical shape with their smaller ends facing one another, aplurality of shoes disposed in spaced circumferential relation about andalong the conical surfaces of each of said elements and carried therebyfor sliding movement radially outwardly in response to axial movement ofsaid elements toward one another, and means carried by said travellerfor substantially simultaneously moving said elements axially toward oneanother thereby to move said shoes radially outwardly into engagementwith the inner walls of the adjacent ends of the pipe sections, saidmoving means including a cylinder carried by one of said elements, apiston in said cylinder carrying a shaft slideably received in a centralpassage through said one element, said shaft being coupled to the otherof said elements for moving the latter in response to displacement ofthe piston in said cylinder.

15. The traveller according to claim 14 wherein said traction assemblyincludes a pair of wheels engageable with the walls of said pipesections, means connecting between said motor and said wheels fordriving the latter, and a third wheel pivotably carried by said tractionassembly on a substantially diametrically opposite side of said tractionassembly from said pair of wheels, and means for biasing said thirdwheel into engagement with the walls of the pipe sections.

17. The traveller according to claim 16 wherein said locating meansincludes means for sensing attainment of a selected axial position bythe traveller along the pipe sections and providing a signal in responsethereto, and means coupled to said motor actuated traction assembly andresponsive to said signal for disabling said motor thereby to locatesaid traveller in said predetermined axial position.

18. The traveller according to claim 17 wherein said locating meansincludes means defining a reference position relative to the pipe jointand a line connecting said reference position means and said traveller,means for paying out said line from one of said traveller and saidreference position means as said traveller moves along the pipe section,said line having a predetermined payed out length when said travellerattains said selected axial position, said sensing means beingcooperable with said line to provide said signal in response to payingout said predetermined length of line.

19. The traveller according to claim 18 in combination with a nest forhousing the traveller, said nest being mounted for movement into axialalignment with a pipe section at the end thereof remote from the pipejoint, said traveller being movable from said nest into the pipe sectionfor location at the predetermined axial position. I

20. The traveller according to claim 14 wherein said shoes are carriedby said elements for axial movement therewith and in a direction tendingto move the pipe sections toward one another.

21. The traveller according to claim 20 wherein said shoes have arcuateouter surfaces substantially conforming to the arcuate inner walls ofthe pipe sections, a pair of discs disposed between said shoes, andmeans for biasing said discs axially away from one another and intoengagement with said shoes on the respective elements to preclude theshoes from cocking relative to one another.

22. The traveller according to claim 14 including means coupled betweensaid traction assembly and said pipe aligner and expander for obtainingmovement of said elements in substantially equal increments toward andaway from one another thereby to preclude movement of the traveller inthe pipe sections when said shoes are moved radially outwardly.

23. The traveller according to claim 14 wherein said moving meansinclude a fluid pressure source, fluid conduits for communicatingpressure fluid between said cylinder on opposite sides of said pistonand said fluid pressure source, and means for selectively communicatingfluid pressure to said cylinder on opposite sides of said piston to movesaid elements toward and away from one another.

24. The traveller according to claim 23 including means coupled betweensaid traction assembly and said pipe aligner and expander for obtainingmovement of said elements in substantially equal increments toward andaway from one another thereby to preclude movement of the traveller inthe pipe sections when said shoes are moved radially outwardly, saidcoupling means including a pinion rotatably carried by said tractionassembly, a first rack carried by said cylinder and in meshingengagement with said pinion, and a second rack carried by said pistonand in meshing engagement with said pinion.

25. The traveller according to claim 14 in a welding apparatus includinga welding station movable longitudinally for alignment with the pipejoint, and means coupled between said welding station and said travellerfor locating said traveller in a predetermined axial position relativeto said pipe joint.

26. The traveller according to claim 14 in an induction weldingapparatus, said welding apparatus including a frame, arcuate inductorcoils carried by said frame for movement between a first positionsubstantially encompassing the pipe joint and a second position spacedfrom the pipe joint.

27. A traveller for disposition in a pair of butting pipe sectionsforming a pipe joint comprising; means for moving said travellerlongitudinally along the pipe sections including a traction assemblyengageable with the inner walls of one of the pipe sections, means forlocating said traveller in a predetermined axial position relative tothe pipe joint including means for sensing a selected axial position ofthe traveller along the pipe section and providing a signal in responseto attainment of said selected position by said traveller, means coupledto said traction assembly and responsive to said signal for deactivatingsaid moving means to locate said traveller at said predetermined axialposition relative to the pipe joint, a pipe aligner and expander coupledto said traction assembly, said pipe aligner and expander including apair of longitudinally spaced elements movable axially toward and awayfrom one another, a plurality of shoes disposed in spacedcircumferential relation about each of said elements and carried therebyfor movement'radially outwardly to engage the inner walls of theadjacent ends of the pipe sections in response to relative movement ofsaid elements, and a nest for housing the traveller, said nest beingmounted for movement into axial alignment with a pipe section at the endthereof remote from the pipe joint, said traveller being movable fromsaid nest into the pipe section for location at the predetermined axialposition.

28. A traveller for disposition in a pair of butting pipe sectionsforming a pipe joint comprising: means for moving said travellerlongitudinally along the pipe sections including a traction assemblyengageable with the inner walls of one of the pipe sections, means forlocating said traveller in a predetermined axial position relative tothe pipe joint including means for sensing a selected axial position ofthe traveller along the pipe section and providing a signal in responsethereto, means defining a reference position relative to the pipe jointand spaced from said axial position, said sensing means including meansfor measuring the distance between said reference position means andsaid selected axial position, and means coupled to said tractionassembly and responsive to said signal for deactivating saidmoving meansto locate said traveller at said predetermined axial position relativeto the pipe joint, a pipe aligner and expander coupled to said tractionassembly, said pipe aligner and expander including a pair oflongitudinally spaced elements movable axially toward and away from oneanother, a plurality of shoes disposed in spaced circumferentialrelation about each of said elements and carried thereby for movementradially outwardly to engage the inner walls of the adjacent ends of thepipe sections in response to relative movement of said elements.

29. The traveller according to claim 28 in an induction weldingapparatus, said welding apparatus including a frame, arcuate inductorcoils carried by said frame for movement between a first positionsubstantially encompassing the pipe joint and a second position spacedfrom the pipe joint.

30. The traveller according to claim 29 wherein said inductor coilscomprise a pluralit of arcuate sections disposed about the pipe oint, anmeans for clamping UNITED sums PATENT OFFICE CE QCEIFICATE OF CQRRECTEONPatent No. 3,697,720 Dated October 10 '1972 In 2 gntg j(3) ChristopherIt is certified that error appears in the above-identified patent andthat saidLeL-ters Patent are hereb corrected as shown below:

In Column 3, line 48, "2a) should read --2 (a) In Column 4, line 6, "atraction" should read --and a traction--.

In Column 13, before line 60, Claim 16 should be entered, and shouldread as follows g ;--l6. The traveller according 'to claim 14 includingmeans for locating said traveller in a predetermined axial positionrelative to the pipe joint.

Signed and sealed this Zhth day of April 1973.

(sEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents ORL' PC -1053 (10-5311- USCOMM-DC 693764 6? UMIED sr-i'rssPATENT OFFICE CERTIFECATE OF CORRECTEQN Patent 150. 3,697,720 DatedOctober 1 ,1972

Inventgyj g ChriStOpher It is certified that error appears in theabove-identified patent and that saidletters Patent are hereby correctedas shown below:

In Column 3, line 48, "2a) should read --2 (a) In Column 4, line 6 "atraction" should read -and a traction---.

In Column 13, before line 60, Claim 16 should be entered, and shouldread as follows -l6. The traveller according to claim 14 including meanse for locating said traveller in a predetermined axial position relativeto the pipe joint.--

Signed and sealed this Zhth day of April 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Y ROBERT GOTTSCHALK Attesting Officer ICommissioner of Patents

1. A traveller for disposition within a pair of butting pipe sectionsforming a pipe joint comprising; means for moving said travellerlongitudinally along the pipe sections including a traction assemblyengageable with the inner walls of one of the pipe sections, a pipealigner and expander coupled to said traction assembly, said pipealigner and expander including a pair of longitudinally spaced elementsmovable axially toward and away from one another, a plurality of shoesdisposed in spaced circumferential relation about each of said elementsand mounted thereon for movement radially outwardly to engage the innerwalls of the adjacent ends of the pipe sections in response to relativemovement of said elements, the respective shoes at like circumferentialpositions about said elements lying in axial alignment one with theother, a plurality of longitudinally extending pins, each of said shoeshaving a recess opening in the direction of the corresponding axiallyaligned shoe, the ends of said pins being receivable in said recesses.2. The traveller according to claim 1 wherein the respective shoes atlike circumferential positions about said elements lie in axialalignment one with the other, and means for maintaining the shoescarried by said elements in respective axial alignment at eachcircumferential location of said shoes about said element.
 3. Thetraveller according to claim 1 including means carried by said pipealigner and expander for maintaining the shoes on each said element in acommon diametrical plane thereby to preclude cocking of the shoes onsaid elements.
 4. The traveller according to claim 1 including means forretaining the ends of said pins in said recesses.
 5. The travelleraccording to claim 1 wherein said elements lie in coaxial relation eachto the other and are generally truncated conical in shape with theirsmaller ends facing one another, and means mounting said shoes forsliding movement along the conical surfaces of said elements in adirection having axial and radial components.
 6. The traveller accordingto claim 5 wherein said shoes have arcuate outer surfaces substantiallyconforming to the arcuate inner walls of the pipe sections, a pair ofdiscs disposed between said shoes, and means for biasing said discsaxially away from one another and into following engagement with saidshoes.
 7. The traveller according to claim 1 where in one of saidelements includes a cylinder, a piston in said cylinder carrying a shaftslideably received in a central passage through said one element, saidshaft being coupled to the other of said elements, said moving meansincluding a fluid pressure source, fluid conduits for communicatingpressure fluid between said cylinder on opposite sides of said pistonand said fluid pressure source, and means for selectively communicatingfluid pressure to said cylinder on opposite sides of said piston to movesaid elements toward and away from one another.
 8. The travelleraccording to claim 1 including means coupled between said tractionassembly and said pipe aligner and expander for obtaining movement ofsaid elements in substantially equal increments toward And away from oneanother thereby to preclude movement of the traveller in the pipesections when said shoes are moved radially outwardly.
 9. The travelleraccording to claim 8 wherein said coupling means includes a pinionrotatably carried by said traction assembly, a first rack carried bysaid cylinder and in meshing engagement with said pinion, and a secondrack carried by said piston and in meshing engagement with said pinion.10. The traveller according to claim 1 in a welding apparatus includinga welding station movable longitudinally for alignment with the pipejoint, and means coupled between said welding station and said travellerfor locating said traveller in a predetermined axial position.
 11. Thetraveller according to claim 10 wherein said welding apparatus includesa frame, and arcuate inductor coils carried by said frame for movementbetween a first position substantially encompassing the pipe joint and asecond position spaced from the pipe joint.
 12. A traveller fordisposition within a pair of butting pipe sections forming a pipe jointcomprising; means for moving said traveller longitudinally along thepipe sections including a traction assembly engageable with the innerwalls of one of the pipe sections, a pipe aligner and expander coupledto said traction assembly, said pipe aligner and expander including apair of longitudinally spaced elements movable axially toward and awayfrom one another, a plurality of shoes disposed in spacedcircumferential relation about each of said elements and mounted thereonfor movement radially outwardly to engage the inner walls of theadjacent ends of the pipe sections in response to relative movement ofsaid elements, said elements lying in coaxial relation each to the otherand being generally truncated conical in shape with their smaller endsfacing one another, means mounting said shoes for sliding movement alongthe conical surfaces of said elements in a direction having axial andradial components, said shoes having arcuate outer surfacessubstantially conforming to the arcuate inner walls of the pipesections, a pair of discs disposed between said shoes, means for biasingsaid discs axially away from one another and into following engagementwith said shoes, the respective shoes at like circumferential positionsabout said elements lying in axial alignment one with the other, aplurality of longitudinally extending pins, each of said shoes having arecess opening in the direction of the corresponding axially alignedshoes, said discs having slots circumferentially spaced thereabout andopening through the outer edges thereof, opposite ends of said pinsbeing receivable in said recesses with intermediate portions of saidpins being receivable in said slots.
 13. A traveller for dispositionwithin a pair of butting pipe sections forming a pipe joint comprising;a motor operated traction assembly engageable with the inner walls ofone of the pipe sections for moving said traveller longitudinally alonga pipe section, a pipe aligner and expander coupled to said tractionassembly for movement therewith, said pipe aligner and expanderincluding a pair of longitudinally spaced elements movable axiallytoward and away from one another, said elements lying in coaxialrelation one to the other and having a generally truncated conical shapewith their smaller ends facing one another, a plurality of shoesdisposed in spaced circumferential relation about and along the conicalsurfaces of each of said elements and carried thereby for slidingmovement radially outwardly in response to axial movement of saidelements toward one another, the respective shoes at likecircumferential positions about said elements lying in axial alignmentone with the other, a plurality of longitudinally extending pins, eachof said shoes having a recess opening in the direction of thecorresponding axially aligned shoe, the ends of said pins beingreceivable in said recesses, and means carried by said traveler forsubstantially simultaneously moving saId elements axially toward oneanother thereby to move said shoes radially outwardly into engagementwith the inner walls of the adjacent ends of the pipe sections.
 14. Atraveller for disposition within a pair of butting pipe sections forminga pipe joint comprising; a motor operated traction assembly engageablewith the inner walls of one of the pipe sections for moving saidtraveller longitudinally along a pipe section, a pipe aligner andexpander coupled to said traction assembly for movement therewith, saidpipe aligner and expander including a pair of longitudinally spacedelements movable axially toward and away from one another, said elementslying in coaxial relation one to the other and having a generallytruncated conical shape with their smaller ends facing one another, aplurality of shoes disposed in spaced circumferential relation about andalong the conical surfaces of each of said elements and carried therebyfor sliding movement radially outwardly in response to axial movement ofsaid elements toward one another, and means carried by said travellerfor substantially simultaneously moving said elements axially toward oneanother thereby to move said shoes radially outwardly into engagementwith the inner walls of the adjacent ends of the pipe sections, saidmoving means including a cylinder carried by one of said elements, apiston in said cylinder carrying a shaft slideably received in a centralpassage through said one element, said shaft being coupled to the otherof said elements for moving the latter in response to displacement ofthe piston in said cylinder.
 15. The traveller according to claim 14wherein said traction assembly includes a pair of wheels engageable withthe walls of said pipe sections, means connecting between said motor andsaid wheels for driving the latter, and a third wheel pivotably carriedby said traction assembly on a substantially diametrically opposite sideof said traction assembly from said pair of wheels, and means forbiasing said third wheel into engagement with the walls of the pipesections.
 17. The traveller according to claim 16 wherein said locatingmeans includes means for sensing attainment of a selected axial positionby the traveller along the pipe sections and providing a signal inresponse thereto, and means coupled to said motor actuated tractionassembly and responsive to said signal for disabling said motor therebyto locate said traveller in said predetermined axial position.
 18. Thetraveller according to claim 17 wherein said locating means includesmeans defining a reference position relative to the pipe joint and aline connecting said reference position means and said traveller, meansfor paying out said line from one of said traveller and said referenceposition means as said traveller moves along the pipe section, said linehaving a predetermined payed out length when said traveller attains saidselected axial position, said sensing means being cooperable with saidline to provide said signal in response to paying out said predeterminedlength of line.
 19. The traveller according to claim 18 in combinationwith a nest for housing the traveller, said nest being mounted formovement into axial alignment with a pipe section at the end thereofremote from the pipe joint, said traveller being movable from said nestinto the pipe section for location at the predetermined axial position.20. The traveller according to claim 14 wherein said shoes are carriedby said elements for axial movement therewith and in a direction tendingto move the pipe sections toward one another.
 21. The travelleraccording to claim 20 wherein said shoes have arcuate outer surfacessubstantially conforming to the arcuate inner walls of the pipesections, a pair of discs disposed between said shoes, and means forbiasing said discs axially away from one another and into engagementwith said shoes on the respective elements to preclude the shoes fromcocking relative to one another.
 22. The traveller according to claim 14including means coupled between said traction assembly and said pipealigner and expander for obtaining movement of said elements insubstantially equal increments toward and away from one another therebyto preclude movement of the traveller in the pipe sections when saidshoes are moved radially outwardly.
 23. The traveller according to claim14 wherein said moving means include a fluid pressure source, fluidconduits for communicating pressure fluid between said cylinder onopposite sides of said piston and said fluid pressure source, and meansfor selectively communicating fluid pressure to said cylinder onopposite sides of said piston to move said elements toward and away fromone another.
 24. The traveller according to claim 23 including meanscoupled between said traction assembly and said pipe aligner andexpander for obtaining movement of said elements in substantially equalincrements toward and away from one another thereby to preclude movementof the traveller in the pipe sections when said shoes are moved radiallyoutwardly, said coupling means including a pinion rotatably carried bysaid traction assembly, a first rack carried by said cylinder and inmeshing engagement with said pinion, and a second rack carried by saidpiston and in meshing engagement with said pinion.
 25. The travelleraccording to claim 14 in a welding apparatus including a welding stationmovable longitudinally for alignment with the pipe joint, and meanscoupled between said welding station and said traveller for locatingsaid traveller in a predetermined axial position relative to said pipejoint.
 26. The traveller according to claim 14 in an induction weldingapparatus, said welding apparatus including a frame, arcuate inductorcoils carried by said frame for movement between a first positionsubstantially encompassing the pipe joint and a second position spacedfrom the pipe joint.
 27. A traveller for disposition in a pair ofbutting pipe sections forming a pipe joint comprising; means for movingsaid traveller longitudinally along the pipe sections including atraction assembly engageable with the inner walls of one of the pipesections, means for locating said traveller in a predetermined axialposition relative to the pipe joint including means for sensing aselected axial position of the traveller along the pipe section andproviding a signal in response to attainment of said selected positionby said traveller, means coupled to said traction assembly andresponsive to said signal for deactivating said moving means to locatesaid traveller at said predetermined axial position relative to the pipejoint, a pipe aligner and expander coupled to said traction assembly,said pipe aligner and expander including a pair of longitudinally spacedelements movable axially toward and away from one another, a pluralityof shoes disposed in spaced circumferential relation about each of saidelements and carried thereby for movement radially outwardly to engagethe inner walls of the adjacent ends of the pipe sections in response torelative movement of said elements, and a nest for housing thetraveller, said nest being mounted for movement into axial alignmentwith a pipe section at the end thereof remote from the pipe joint, saidtraveller being movable from said nest into the pipe section forlocation at the predetermined axial position.
 28. A traveller fordisposition in a pair of butting pipe sections forming a pipe jointcomprising: means for moving said traveller longitudinally along thepipe sections including a traction assembly engageable with the innerwalls of one of the pipe sections, means for locating said traveller ina predetermined axial position relative to the pipe joint includingmeans for sensing a selected axial position of the traveller along thepipe section and providing a signal in response thereto, means defininga reference position relative to the pipe joint and spaced from saidaxial position, said sensing means including means for measuring thedistance between saId reference position means and said selected axialposition, and means coupled to said traction assembly and responsive tosaid signal for deactivating said moving means to locate said travellerat said predetermined axial position relative to the pipe joint, a pipealigner and expander coupled to said traction assembly, said pipealigner and expander including a pair of longitudinally spaced elementsmovable axially toward and away from one another, a plurality of shoesdisposed in spaced circumferential relation about each of said elementsand carried thereby for movement radially outwardly to engage the innerwalls of the adjacent ends of the pipe sections in response to relativemovement of said elements.
 29. The traveller according to claim 28 in aninduction welding apparatus, said welding apparatus including a frame,arcuate inductor coils carried by said frame for movement between afirst position substantially encompassing the pipe joint and a secondposition spaced from the pipe joint.
 30. The traveller according toclaim 29 wherein said inductor coils comprise a plurality of arcuatesections disposed about the pipe joint, and means for clamping saidsections one to the other to substantially fully encompass the pipejoint.